There is a continuing need for improvements in hammers for use with hammermills, shredders and rotary crushers. Such devices have been known for a long time, but a basic problem in this art has never been solved, that is, the problem of obtaining maximum shredding, crushing, or hammering action while minimizing the amount of metal hammer which is discarded after the hammer has worn to a point necessitating replacement or repair.
In the past, attempts have been made to solve this problem by providing hammers which have replaceable tips secured to the hammer shank by pins or other locking devices. However, such attempts have not been completely successful. The locking devices such as bolts, nuts, pins, wedges, and the like that have been used to fasten the tips to the shaft of the hammer, of necessity, have been made of less impact resistant materials than the hammer or tip and as a result have generally worn faster than the hammer tip or shaft. When a locking device fails, a tip can become unattached and because of its high impact resistant nature, become an instrument of destruction destroying additional tips and shredder components. In addition, both the points where the tips are connected to the shaft and the bolts, nuts, pins, wedges and the like tend to "lime" up or become impacted with finely ground material making it very difficult to remove the locking device and separate the tip from the shaft.
Representative of the types of two-piece hammers that have been employed in the past are those shown and illustrated in U.S. Pat. Nos. 2,531,597, 2,605,972 and 3,510,076. Although the improvements disclosed in the above patents do provide some advantages over singlepiece hammers they are not completely satisfactory.